Have no idea whether burglars break into your home in your absence? Have you ever imagined that your home lights up at once when you open the door? Or wanna your bed-room light turns off automatically once you walk into the living-room? Any of your ideas will be reality with SONOFF DW2-Wi-Fi wireless door/window sensor. DW2-Wi-Fi comes in two pieces, the transmitter fits onto the door or window and the magnetic switch attaches to the frame. It can help secure your door or window to let you know whether your home is safe wherever you are. The sensor will trigger an alarm to your smartphone to remind you of an intruder when the door or window is opened. Connect SONOFF wireless IP camera and you can view who the intruder is on the sensor page of APP. Whenever your door or window is opened or closed, you can check the real-time opening and closing status on eWeLink APP. Real-time battery level display and low-battery reminder ensure you get clear know how long the sensor can run and when you need to replace batteries. With simple peel and stick installation, it is easy to fit in door frames and window sills.